MY PET IS SCRATCHING:
UNDERSTANDING YOUR DOG’S ALLERGIES.

November 2006 - by Doctor Denise E. Roche, D.V.M.
To read the second of these two articles - click here  

BACKGROUND:

Fall in the Ozarks brings less humidity, cooler weather, colored leaves, and unfortunately ragweed.  Fall means hay fever symptoms in people and allergic dermatitis in our pets. Unlike humans, most pets show signs of allergies through their skin. What exactly is an allergy? An allergy is a state of over-reactivity or hypersensitivity to an allergen. Most allergens are proteins. The allergen protein may be of insect, plant or animal origin.  Some allergens are inhaled, some allergens are ingested and some allergens cause contact irritation. No matter the route of exposure, the end result is an itchy dog if your pet suffers from allergies.

The itching is caused by an overactive immune system reaction. This can sometimes happen with the first allergen exposure but often it requires multiple exposures to the offending allergen. An antibody in the blood called Immunoglobulin E (IgE) binds to the allergen protein.  This allergen-IgE complex then attaches to a Mast Cell. When attached to an allergen complex, Mast Cells break up and release potent inflammatory compounds such as histamine. This starts the inflammatory cascade and the allergic reaction. This allergic reaction can happen anywhere on the skin of your dog.  The medical term for this is allergic dermatitis or atopy.

ALLERGENS:

There are numerous substances that can act as allergens. Flea saliva, tick saliva, tree pollens (cedar, oak, ash), flower pollens, grasses and weed pollens (ragweed), as well as molds, mildew, and house dust mites are the most common allergy offenders.  Some plant and animal proteins found in foods can cause allergies as well as some food additives.  The most common cause of allergies in our pets is fleas and the least common cause of allergies is food.  Up to 80% of our pets with allergic dermatitis are very allergic to fleas so flea control is absolutely essential in the allergic pet.

The most common sign of allergies is itching of the skin –either in one area or generalized over the body. Itchy signs can include chewing and licking of the feet, rubbing or pawing at the face or eyes, rubbing the head or ears along the carpet or sofa, rubbing the belly or rear on the floor, and redness of the skin in the affected areas.  Many pets will lick their armpits, thighs, belly or abdomen. Scratching at the ears or ear flicking and head shaking is also indicative of allergies. The constant scratching and licking can result in a secondary bacterial skin infection.  Other signs of allergies may also include reoccurring ear infections, full anal glands and anal gland infections. 

BREEDS PREDISPOSITION:

Many dog breeds are predisposed to allergies.  Terrier breeds as a group are the most commonly affected dogs that we see in our practice. Schnauzers, Westies, Scottish, Cairn, Welsh, Fox, Boston and Jack Russell Terriers are just a few that can be afflicted with allergies.  Golden Retrievers, Labrador Retrievers, Boxers, Bulldogs, Shih Tzus, Cocker Spaniels, and Shepherds are also commonly affected breeds.   Most pets will start showing allergy signs between one and three years of age.  Initially, many allergies will occur seasonally when the allergen is at its peak.  But each year, the allergy season starts a little earlier and lasts a little longer and the allergies worsen. Eventually with time, allergic dermatitis can become year-round.  Allergens such as house dust mites, molds and mildew are present any season and pets sensitive to these will suffer year-round.

TREATMENT:

The best way to treat allergies is to individualize the treatment to your pet and to treat that patient with the lowest dose or frequency of medication possible because allergies are a life long problem. Eventually your pet may need medication daily to control its allergies so starting with lower dose therapy initially will be of benefit. Keep in mind that some animals will respond better to different aspects of the therapy than others and some therapies may not work at all.  Also remember that allergies are controlled and not cured. Seven possible allergy treatments include frequent bathing, antihistamine therapy, fatty acid supplementation, steroid therapy, cyclosporine therapy, desensitization therapy, and/or food allergy trial.  And as mentioned earlier flea and tick control is essential in the allergic patient.  Each of treatment areas will be discussed next month.

To read the second of these two articles - click here